The typical Goex load is the same dipper for shot and powder.

If you use a 7/8 ounce load of shot,
use the same dipper for GOEX FF black powder.

Use the appropriate height of wad fillers and that should do it.

If you use RMC hulls then 12 gauge wads are ok
For others use 11 gauge like Der Ami has stated smile

http://circlefly.com/html/wad_sizing_chart.html

Mike